Dr David Gregory
BBC News, science & environment correspondent
Sam Oliver spotted something suspicious about his connection
In the attic office of his home outside Shrewsbury, Sam Oliver has a lovely view of his back garden and also a successful IT business.
And, since it's a business, he pays BT a business rate for his link to the web.
But for a while Mr Oliver has been suspicious that something is going on with his internet connection and that at certain times of the day some programmes were having trouble.
"The speeds for using the BBC iPlayer gets very slow and unusable essentially," he said.
So he decided to investigate.
He installed a piece of hardware provided by SamKnows, which is not linked to Mr Oliver despite his first name, which would independently set his BT line a number of tests throughout the day. It was part of a test across the country.
First the good news, for surfing the web BT came out tops in terms of speed.
But when he looked into the results for his individual connection it quickly became clear why.
Although simple internet surfing of web pages was fine, other internet usage was being drastically curtailed by BT.
Mr Oliver discovered the speed of his so called peer-to-peer downloads could sometimes be reduced to zero. Peer-to-peer (or P2P) is a clever way for users of the internet to upload and download large files.
BT said it only restricts speeds for heavy internet users
But according to Mr Oliver: "Anything that uses file-to-file or peer-to-peer on BT just falls over."
In the past, associated solely with illegal downloads of films and music P2P technology has now been adapted by broadcasters such as Channel 4 and the BBC to deliver television programmes over the web.
But what Mr Oliver (and the wider report from Sam Knows) discovered is that BT is shaping P2P traffic. Reducing the data flow at certain times of day. According to the test sometimes throttling it back down to zero. But why?
BT told BBC News: "We restrict P2P speeds if it's having a negative impact on the online experience of the majority of our customers.
"We normally place restrictions in the evenings at peak time, but we do apply them during the day if a lot of customers are using P2P at the same time.
"Without these limits all our customers using their broadband service would suffer, regardless of whether they are using P2P or not."
BT said it only does this for so-called "heavy" users and that all this is clearly set out in the terms and conditions of its service.
But what this survey concludes is that in fact all P2P traffic is being shaped by BT regardless of whether you are a heavy user or not.
Which means legitimate P2P software used to download TV and radio from the BBC iPlayer and 4OD from Channel 4 will run at just a fraction of the potential speed BT can deliver.
BBC executives have threatened to "name and shame" internet service providers who shape P2P traffic as BT is doing.
The BBC's former Director of the Future Media and Technology group Ashley Highfield said: "Content providers, if they find their content being specifically squeezed, shaped, or capped, could start to indicate on their sites which ISPs their content worked best on (and which to avoid)."
So far it has not come to that.
In the meantime the advice for customers is read those terms and conditions to make sure your internet service doesn't suddenly slow to a trickle.
Mr Oliver remains angry though "Ultimately it's not my problem that BT can't provide enough through put on their network"
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